I use pocket cameras , exclusively. I did own the SD870IS and was happy with it, except for the low light capability......really not that bad as a pocket camera , for its time....but now, with the S100, I am very satisfied with the night/ indoor/ low light results ..as well. I would have kept the SD870IS as a backup, but I dropped it in water and ruined it. What I miss most is the capability of the SD870IS to stand upright for self-timer photos

However, the S100 is just about all I could ask for in a pocket camera ....

I've got many S100 low light photos posted in my gallery , if you care to check them out.